The invention relates to CMOS imager devices and plastic packaging thereof.
Image sensors typically are formed using some kind of clear portion to allow light photons to enter the package. Other packaging techniques use plastic injection molds, blown plastics, or plastic transfer molds.
These techniques use a flow of plastic packing compound into a cavity. The cavity includes an imager die to be packaged, on a lead frame. Once cooled, the package part is removed from the mold, and the leads are trimmed or formed to form the final packaged part.
Typical materials used in the package molding have been opaque. These materials block incoming light. Hence, when these materials are used to package an optical component, they must be used in a way that does not interpose packaging material between the light and the component.
These prior art systems have been used with a preformed plastic cavity leadless chip carrier. Using these forms, however, results in higher package cost.
The invention relates to packaging a photosensitive device in a clear package. More specifically, the photosensitive device can be a CMOS image sensor that is packaged in clear QFP (Quad Flat Package) or acrylic. The clear material allows the CMOS image sensor to be packaged in the same way as any other CMOS device. Since the material used to package the device is clear, the image sensor can be directly packaged in the package. This new packaging means results in lower cost devices that are more readily integrated with acrylic optics.